Permeability of rosmarinic acid in Prunella vulgaris and ursolic acid in Salvia officinalis extracts across Caco-2 cell monolayers

Ethnopharmacological relevanceRosmarinic acid (RA), a caffeic acid-related compound found in high concentrations in Prunella vulgaris (self-heal), and ursolic acid (UA), a pentacyclic triterpene acid concentrated in Salvia officinalis (sage), have been traditionally used to treat inflammation in the mouth, and may also be beneficial for gastrointestinal health in general.Aim of the studyTo investigate the permeabilities of RA and UA as pure compounds and in Prunella vulgaris and Salvia officinalis ethanol extracts across human intestinal epithelial Caco-2 cell monolayers.Materials and methodsThe permeabilities and phase II biotransformation of RA and UA as pure compounds and in herbal extracts were compared using Caco-2 cells with HPLC detection.ResultsThe apparent permeability coefficient (Papp) for RA and RA in Prunella vulgaris extracts was 0.2 ± 0.05 × 10−6 cm/s, significantly increased to 0.9 ± 0.2 × 10−6 cm/s after β-glucuronidase/sulfatase treatment. Papp for UA and UA in Salvia officinalis extract was 2.7 ± 0.3 × 10−6 cm/s and 2.3 ± 0.5 × 10−6 cm/s before and after β-glucuronidase/sulfatase treatment, respectively. Neither compound was affected in permeability by the herbal extract matrix.ConclusionRA and UA in herbal extracts had similar uptake as that found using the pure compounds, which may simplify the prediction of compound efficacy, but the apparent lack of intestinal glucuronidation/sulfation of UA is likely to further enhance the bioavailability of that compound compared with RA.